Brachytherapy is the delivery of a course of radiation therapy to a body site by placing the radiation source into the body site. Usually, an implantable device (e.g., catheter, cannula, or applicator) is inserted into the body site and later a radiation source is inserted through the catheter and into the body site. Radiation therapy may be administered through one of several methods, or a combination of methods, such as interstitial or intercavity brachytherapy. Brachytherapy may also be administered using radioactive sources or electronic sources, such as x-ray sources, for example.
Conventional methods of determining the precise location that the radiation source(s) should be inserted into the catheter include inserting a calibrated marker wire into the catheter and using external imaging (e.g., radiographic, MRI, or ultrasound). From the resultant images, the precise position of the target tissue relative to the catheter and the inserted calibrated wire may then be determined. Once the position of the target tissue is known relative to the catheter and the calibrated wire, the location for positioning the radiation source within the catheter may then be calculated. The optimal dwell times for source treatment position are also determined using commercially available software. These activities are collectively called treatment planning.
Determining the precise location of the target tissue (i.e., the position of the radiation source(s)) is a critical step in the treatment planning process. Use of conventional methods using external imaging to determine target tissue location have several disadvantages including increased time and cost, as well as problems arising from miscalculation of offset distances and problems arising from slipping or movement of the catheter after the external imaging has been completed but before the treatment has been completed.
Therefore, it would be desirable to have devices and methods for precisely locating the position of the catheter relative to the target tissue (i.e., position of the radiation source(s)) to enhance treatment planning. Disclosed herein are graduated transparent catheters, and methods for using same, configured to provide direct visualization and identification of target tissues (i.e., position of the radiation source(s)).